The present invention relates to a method for the preparation of polyacetylene or, more particularly, to a method for the preparation of high-purity polyacetylene in a bulky form by solid-state polymerization reaction.
It is well known and widely practiced to prepare polyacetylene or polymer of acetylene by the catalytic polymerization reaction of acetylene conducted on the surface of an organic solution of a so-called Ziegler-Natta catalyst, in which the polymerization reaction proceeds at or in the vicinity of the gas-liquid interface [see, for example, T. Ito et al., Journal of Polymer Science, Polymer Chemistry Edition, volume 12, page 11 (1974)].
The polymer of acetylene in this prior art method is obtained in the form of a film composed of a loose web of fibrils having a diameter of several tens of nanometers. Such a web of fibrils or felt-like film naturally contains void spaces between the fibrils so that the polymer film has a low bulk density of only one third to a half of the true density thereof [see, for example, J. C. W. Chien et al., Journal of Polymer Science, Polymer Letter Edition, volume 20, page 97 (1982)] and the film can never have high transparency.
Another problem in the above mentioned catalytic polymerization reaction is that the polymer as prepared necessarily contains considerable amounts of the metals as the constituents of the catalyst, organic solvent and the like as impurities. Purification of the polymer by completely removing the impurities is an extremely difficult matter because the impurities chemically included in the fibrils cannot be washed out by a washing treatment although the impurities physically contained in the spaces between the fibrils may possibly be removed. Thus, there has been no prior art method which produces polyacetylene having a sufficiently high purity.